Send array with Ajax to PHP script

Encode your data string into JSON.

dataString = ??? ; // array?
var jsonString = JSON.stringify(dataString);
   $.ajax({
        type: "POST",
        url: "script.php",
        data: {data : jsonString}, 
        cache: false,

        success: function(){
            alert("OK");
        }
    });

In your PHP

$data = json_decode(stripslashes($_POST['data']));

  // here i would like use foreach:

  foreach($data as $d){
     echo $d;
  }

Note

When you send data via POST, it needs to be as a keyvalue pair.

Thus

data: dataString

is wrong. Instead do:

data: {data:dataString}